1. Field of the Invention
The present invention relates to a joint fastening structure for an automotive power plant fastening portion in which an accessory is jointly fastened to the fastening portion.
2. Description of the Related Art
In a conventional power plant in which a transmission is integrally connected to an end face of an internal combustion engine on an output shaft end side, since an accessory needs to be disposed within a predetermined narrow space in an engine compartment, the accessory is secured to the housing at a portion of the internal combustion engine main body which is contiguous with the transmission with threaded components such as bolts and screws, and the housing is fastened to the cylinder block with threaded components. In addition, the cylinder block and the transmission case are fastened together with threaded components.
In a mounting structure as described above, however, since the fastening portion where the accessory is mounted on the housing and the fastening portion where the housing is mounted on the internal combustion engine main body interfere with each other, there is caused a drawback that the disposition of the accessory is limited whereby the degree of freedom in layout of the accessory is reduced.
The present invention relates to an improved automotive power plant fastening portion which has overcome the difficulty, and according to a first aspect of the invention, there is provided a joint fastening structure for an automotive power plant fastening portion which is commonly used as a fastening portion of an internal combustion engine main body and a transmission case and a fastening portion of said internal combustion engine main body and an accessory, the joint fastening structure being characterized in that a threaded component passes through the transmission case and the internal combustion engine main body so as to be integrally fastened to internal threads in the accessory.
According to the first aspect of the invention, with the aforesaid structure, since the threaded component is inserted from the transmission case side, the internal combustion engine main body and the transmission case can easily be fastened together without being influenced by the mounting configuration of the accessory to the housing and the other accessories.
In addition, since the accessory is jointly fastened to the internal combustion engine and the transmission which constitute the automotive power plant with the threaded component which integrally combines the internal combustion engine with the transmission, the fastening man-hours and number of fastening components can be reduced, and this leads to reduction in cost.
In addition, according to a second aspect of the invention, portions at which the threaded component passes through the transmission case and the internal combustion engine main body are flanges. According to the construction of the second aspect of the invention, since the flange portions of the internal combustion engine main body and the transmission case are highly rigid, in addition to the advantage provided by the first aspect of the invention, there is provided an advantage that the fastening strength can be increased.
Furthermore, according to a third aspect of the invention, the threaded component is disposed in the vicinity of a mating surface between the cylinder block and the oil pan. According to the construction of the third aspect of the invention, since the threaded component for use in attaching the accessory is allowed to pass through the highly rigid portion in the vicinity of the mating surface between the cylinder block and the oil pan, in addition to the advantages provided in accordance with the first and second aspects of the invention, there is further provided an advantage that the fastening strength of the accessory relative to the internal combustion engine main body and the transmission case can further be increased.
In addition, while the accessory itself tends to be heated by virtue of heat conducted from the cylinder block of the internal combustion engine, according to a fourth aspect of the invention, a cooling water pipe member communicating with a radiator is disposed along the vicinity of the accessory. Thus, in addition to the advantages provided in accordance with the first, second and third aspects of the invention, there is provided an advantage that the accessory can be cooled by cooling water to thereby improve the durability since the temperature of the cooling water passing through the interior of the cooling water pipe member is lower than that of the accessory.